Currently it's not hard for a software developer to find a job, especially those that YC startups would want to hire.
So I don't think stability is much of an issue in the current economy, developers are not afraid to lose their job because they know they'll have dozen of opportunities just by activating their network.
Even with that being the case finding a new job is a hassle and means you have an interruption in pay and insurance. Gives me a lot of incentive to just work at BigCo and not worry about it until -I- want to worry about it.
So I don't think stability is much of an issue in the current economy, developers are not afraid to lose their job because they know they'll have dozen of opportunities just by activating their network.